Joint forming structure



Oct. 4, 1966 w. F. MIDDLESTADT 3,276,335

JOINT FORMING STRUCTURE 2 Sheets-Sheet 1 Filed Jan. 8, 1964 |6c'. NY NWILLIAM F. M lDD LEJSTADT- ATTORNEYS 1 Oct. 4, 1966 w. F. MIDDLESTADT3,273,335

JOINT FORMING STRUCTURE 2 Sheets-Sheet 2 Filed Jan. 8, 1964 A TTORNE'YSUnited States Patent Ofifice 3,276,335 Patented Oct. 4, 1966 3,276,335JOINT FORMING STRUCTURE William F. Middlestadt, Arnold, Md. (200 E.Joppa Road, Baltimore, Md.) Filed Jan. 8, 1964, Ser. No. 336,572 10Claims. (CI. 94-18) This invention relates to an improved method forforming joints in a settable composition and to an improved jointforming structure.

The invention has particular utility in forming joints in concreteroadways, air strips, walls, and the like.

It is an object of the present invention to provide an improved methodof forming joints in concrete pavement and the like which eliminates thepossibility of infiltration of foreign material into the joints to beformed as the joint forming structure initially completely fills andforms the joint and maintains said joint to provide a smoothsubstantially uniform top surface generally coplanar with the extendedsurface of the pavement and the like.

A further object of the present invention is to provide such a jointforming method and structure which requires a minimum of sealingcompound.

A further object is to provide such a method and structure whichsubstantially reduces the on-the-job cost of forming joints in concretepavements and the formation of the joints is not effected by thehardness of the aggregate in the concrete and concrete cracking iscontrolled to provide a smooth riding surface.

A further object of the present invention is to provide an improvedmethod of forming joints in concrete and the like and a concrete and thelike joint forming structure which requires a minimum maintenance.

These and other objects and advantages are provided in a joint formingstructure which generally comprises a pair of opposed extended surfaceelements adapted to be embedded in a settable composition, resilientmeans between at least the upper opposed surfaces of said elements, andreleasable means maintaining said elements in compressing relationshipto the resilient means; and by a method of forming a joint in a settablecomposition comprising inserting a joint forming member having a pair ofopposed extended surface elements with resilient means between at leastthe upper opposed surfaces thereof and releasable means maintaining saidelements in compressing relation to the resilient means, into thesurface of a mass of a settable composition with the resilient meanssubstantially flush with an exposed surface of the settable mass, andthereafter bringing about the release of the releasable means.

The invention will be more particularly described with reference to theillustrated embodiments thereof shown in the accompanying drawingswherein:

FIG. 1 is a perspective view of a portion of a joint forming structureembodying the principles of the present invention;

FIG. 2 is a sectional view of the structure illustrated in FIG. 1embedded in a concrete roadway with the releasable means removed;

FIG. 3 is a fragmentary view similar to that illustrated in FIG. 2 of afurther form of the present invention;

FIG. 4 is a perspective view of a further form of joint formingstructure constructed in accordance with the teachings of the presentinvention;

FIG. 5 is an enlarged fragmentary view of the structure illustrated inFIG. 4 embedded in a concrete roadway with the joint substantially atits maximum expansion;

FIG. 6 is a perspective view of a further form of joint formingstructure constructed in accordance with the teachings of the presentinvention;

FIG. 7 is a fragmentary sectional view of the joint forming structureillustrated in FIG. 6 embedded in a concrete roadway with the formedjoint in a substantially fully expanded position;

FIG. 8 is a fragmentary sectional view of another form of the presentinvention illustrating the joint forming structure embedded in aconcrete roadway;

FIG. 9 is a perspective view of a modified form of resilient meanssuitable for use with the assemblies shown, for example, in FIGS. 1, 4,6 and 8; and

FIG. 10 is a fragmentary perspective view of another form of jointforming structure constructed in accordance with the teachings of thepresent invention.

Referring to FIGS. 1 and 2 of the drawings, 10a generally designates oneform of the improved joint forming structures. The joint formingstructure 10a is constructed from a single sheet of metal which is bentor folded to provide a pair of extended surface leg elements 12a and14a. Each of the leg elements is provided with a recurved portion 16aand 16a adjacent its lower end which form a pair of generally U-shapedchannels. The upper portion of the metal sheet is folded or formed intoa channel 18a generally rectangular in cross section having side walls20a and 22a, a bottom 26a and a top 24a. The bottom 26a is formed with apair of depending flangelike elements 28a and 30a.

Within the quadrangular channel 18a formed by the sides 20a, 2211, thebottom 26a and the top 24a is positioned a compressed elastomericresilient member 32a. The elastomeric member 32a may comprise a naturalor synthetic rubber or other resilient material. Preferably, theelastomeric material is one that will resist the solvent action ofhydrocarbon fuels, oils and greases and will maintain its resiliencyduring normal atmospheric temperature changes. The elastomeric materialknown as neoprene has been found to provide very satisfactory results.The side walls of the resilient member 32a are bonded as indicated at33a to the inner faces of side walls 20a and 22a of the sheet metalmember and the assembly is maintained in its compressed illustratedconfiguration by the top 24a and by a plurality of separable fasteners34a.

The separable fasteners 34a illustrated in FIGS. 1 and 2 are simplyformed by merely spike-punching a portion of the metal forming, forexample, leg 14a through leg 12a. In order to release the releasablemeans maintaining the elastomeric material 32a in its compressedassembled form, lines of weakness or score lines 36a and 38a areprovided in the top 24a adjacent the line of juncture of the top withthe respective side walls 20a and 22a.

In operation of this form of the invention, the assembly as illustratedin FIG. 1 is inserted in a settable composition such as a concreteroadway following the pouring of the roadway with the extended surfaceleg portions 12a and 14a projecting into the concrete and with the topwall 24a of the assembly generally flush with the extended top surface40 of the concrete 42. Referring particularly to FIG. 2 of the drawings,it will be seen that concrete sets within the channels 16:: and 16a atthe lower end of the assembly and also within the channels formed by thedepending portions 28a and 30a adjacent the bottom of the quadrangularchannel formed at the top of the structure. As soon as the concrete 42has received its initial set, the top 24a is stripped from the assemblyas shown in broken lines in FIG. 1; the stripping of the top portionbeing rendered relatively simple in view of the lines of weakness 36aand 38a. With the top 24a stripped from the assembly as the concretecontinues to set and assume its initial contracted form, the separablefasteners 34a release as the shrinking concrete gripping the U-channelsat the upper and lower ends of the extended surface leg members 12a and14a place parting forces on these ele- & mentswhereby the assemblyassumes a position such as illustrated in FIG. 2.

After the concrete 42 has set the roadway, as far as the joint formingstructure is concerned, is ready for immediate use.

It will be particularly noted from the foregoing discussion of theoperation of the improved joint forming struc ture that the jointforming structure permits the formation of joints in concrete roadwaysand the like with a minimum of on-the-job labor and provides a jointwhich is always maintained free of foreign matter.

Where desired, the outer surfaces of the extended surface leg members12a and 14a, including the outer surfaces of the side walls 20a and 22a,may be provided with a surface which will bond to the settablecomposition during setting thereof. In FIGS. 1 and 2 the bond assistingsurface comprises an adhesive coating 19a and granular elements 21apartially embedded therein. The adhesive may comprise a liquidrubber-like cement, a thermoplastic or thermosetting plastic compositionand the like and the granular elements 21a may comprise relatively finecrushed silica rock, sand, iron powder or grains, etc., which willprovide a rough surface which will readily bond to the concrete roadway.It is also contemplated that the coating may comprise a porous material.

Referring to FIG. 3 of the drawings, a modified form of the jointforming structure is illustrated in place in a concrete roadway 42. Themodified joint structure 10b is formed in a manner similar to the jointforming structures illustrated in FIGS. 1 and 2 except that theelastomeric resilient material 32b, bonded as at 33b to the upper endsof the metal sheets, comprises an extruded or molded rubber-like channelelement having air channels 44 surrounded by integral webs of theresilient material. This form of sealing means obtains its resiliencefrom the nature of the material and from the existence of the airchambers 44.

With this form of the invention the ends of the resilient material 32bmay be sealed and a vacuum drawn on the air channels 44. The vacuum willhold or assist in holding the resilient member in compressedrelationship to the extended surface leg members. Puncturing of the endseals, after the joint forming member is inserted in the settableconcrete, will bring about release of the resilient member 32b. Furtherpressure fluid may be pumped into the channels 44 after the vacuum isreleased to increase the resilient pressure of the resilient member 32b.

Referring to FIGS. 4 and 5 of the drawings, another form of jointforming structure is generally illustrated at c. The joint formingmember 10c depends solely on the shrinking of the settable compositionto effect release of the compression of the compressed resilient member.In FIGS. 4 and 5, the joint forming member 100 includes a pair ofextended surface leg members 120 and 140. The

lower edges of each of the leg forming members 120 and 140 are re-curvedat 16c and 160' and the top of each of the leg forming members aregenerally formed as opposed L-shaped structures 48c and 500. Attached tothe L- shaped members is a resilient web 320 which in its compressedposition is generally M-shaped as illustrated in FIG. 4. and in itssubstantially fully expanded position is generally inverted U-shaped incross section. The pair of legs 52c and 54c 0f the resilient web 320 arebonded by an adhesive or, for example, by heat sealing to the uprightportions of the respective L-shaped elements 480 and 500, respectively.The assembly is held in the compressed configuration as illustrated inFIG. 4 by a plurality of separable fasteners generally designated 340which separable fasteners, in the illustrated form of the invention, areidentical to the separable fasteners 34a of the form of the inventionshown in FIGS. 1 and 2. The assembly also includes a plurality ofstruck-out portions 560, in each of the leg members, which struck-outportions are adapted to be embedded in the concrete 42 as more clearlyillustrated in the sectional view, FIG. 5,,

L1- and cooperate with the re-curved lower edges 16c and 16c of each ofthe leg members 120 and 14c in effecting release of the separablefasteners 34c upon shrinking or contraction of the concrete 42.

In operation of this for-m of the invention, the assembly as illustratedin FIG. 4 is inserted in the unset concrete with the top edges of theresilient element 320 generally flush with the top 40 of the roadway. Asthe concrete sets and shrinks, the separable fasteners 340 are pulledloose by the contractional forces applied to each of the leg members bythe concrete gripping the generally U- shaped re-curved portions 160 and160 and the struck-out portions 560. Expansion of the formed jointcauses the' resilient member 320 to return generally to its folded orcompressed configuration as illustrated in FIG. 4. It will beparticularly noted that in this form of the invention once the elementis inserted within the settable composition, no further steps must betaken by the paving contractor in order to provide the novel joint seal.

Another form of the joint forming structure of the invention isillustrated in FIGS. 6 and 7. The joint forming structure illustrated inFIGS. 6 and 7 is generally designated 10d and includes a pair ofextended surface leg portions 12d and 14d having re-curved lower edges16d and 16d. The re-curved edges 16d and 16d cooperate with re-curvedportions d and 60d to provide dove tailed-like channels which receivethe concrete as illustrated in FIG. 7 and assist in releasing theseparable fasteners 34d. Further, concrete gripping elements are formedby channels 64d and 66a! in extended surface leg members 12d and 14d.The upper end of the element has a center section 68d of generallyM-shaped configuration which cooperates with side walls 70d and 72d togrippingly engage the legs 52d and 54d for securing the resilient member32d to the metallic extended surface leg elements. The generallyM-shaped bridge member 68d is formed with a line of weakness at 36dwhich corresponds to one of the lines of weakness 36a or 38a of the formof the invention illustrated in FIG. 1.

In operation of this form of the invention, the assembly 10d .isinserted when generally in the configuration illustrated in FIG. 6 intothe unset concrete 42 with the top surface of the resilient element 32dgenerally flush with the top 40 of the concrete roadway. After theconcrete has taken its initial set, a tool is inserted in the top of theportion 74d of the resilient member 32d and downward pressure causes thebridge element 680. to break loose at its line of weakness 36d therebyreleasing the upper end of the assembly as generally illustrated in FIG.7 while the lower end is released by contraction of the concrete whichreleases the separable fasteners 34d. appreciated that said line ofweakness may be either along line 36d or 38d or both or at the apex ofthe bridge member 68d. Where only one line of weakness is employed, theelement is not free to fall into the space between the leg members 12dand 14d, thereby avoiding all possibilities that the released elementmight position itself at a point which would prevent complete reclosingof the joint during expansion of the concrete slabs 42.

Referring to FIG. 8, 102 designates a modified form of the joint formingstructures of the invention.

In this form of the device, the generally M-shaped resilient element 32eis provided with a pair of re-curved edges 78c and 80e which arereceived in re-curved portions 822 and 84e, respectively, of the upperends of extended surface leg portions 12c and 14e. Since this form ofthe invention does not have a bridge member such as bridge member 68d tomaintain the upper portions of the extended surface leg members 12c and14e together when the device is in the resilient element compressedrelationship, the re-curved channel forming portions 64:: and 66ecorresponding to the channel-forming portions 640! and 66d of the formof the invention illustrated in FIGS. 6 and 7 are provided withreleasable fasteners 34:: similar in COIlSfiUGfiOn to the releasablefasteners 34 a, c and d of It will be the forms of the inventionillustrated in FIGS. 1 through 4 and 6.

The form of the invention illustrated in FIG. 8, like the form of theinvention illustrated in FIGS. 4 and 5, does not require manual releaseof the resilient element 32e as the initial contraction of the concrete42 brings about release of the upper releasable fasteners 34c andcorresponding lower releasable fasteners not shown in FIG. 8 of thedrawings.

Referring to FIG. 9, a modified form of resilient element isillustrated. The illustrated resilient element 32] is generally in theform of a U-shaped channel having depending leg portions 90 and 92 and abridge portion 94] which bridge portion folds downwardly as illustratedin dotted lines when the leg portions 90 and 92 are urged toward eachother. The resiliency of the resilient element 321 is augmented orprovided by a plurality of spring wires 96 embedded within the top andleg portions of the elemeat 32 The particular configuration of theresilient element 32 is illustrated as adaptable for use with the formsof the joint forming members illustrated in FIGS. 4, 5, 6 and 7. It willbe apparent, however, that with minor modifications of the configurationof the resilient element 32], it may be employed with the otherdescribed forms of the invention.

A further form of the joint forming member is illustrated at g in FIG.10. In this form of the invention, the extended surface leg portions 12gand 14g and the top bridge portion 91g of the resilient element 32g areintegrally formed from, for example, a natural or synthetic elastomericmaterial and the elastomeric material is molded, cast or extruded withshaped resilient spring elements 96g therein. The elastomeric member 10gand its reinforcing spring wires 96g are shaped to provide concreteengaging re-curved bottom edges 16g and 16g and 98g, 100g, 102g and104g. In order to maintain the top 91g in the compressed configurationas illustrated in FIG. 9, opposed faces 106g and 108g and opposed faces110g and 112g are attached by separable fastening means which maycomprise suitable adhesives which are applied to portions of saidopposed faces and the element thereafter clamped in the compressedconfiguration until said adhesives are set. Also, these faces may besecured by heat sealing where the composition of the elastomericmaterial is susceptible to a heat sealing operation or suitable grippertype fasteners may be molded into the elastomeric material during theformation of the element. This form of the invention, like the formsillustrated in FIGS. 4, 5 and 8, does not require an operator to releasethe releasable sealing means as initial contraction of the concretebrings about said release.

Further, where desired, the top element 91g, when folded into itscompressed Mconfiguration, may be releasably held in the compressed formby a suitable adhesive. The release of the adhesive may be brought aboutby applying a solvent for the adhesive to the top surface 91g after thedevice has been inserted in the concrete and initial setting of theconcrete has taken place.

It will also be apparent that an adhesive and solvent could be used withthe forms of the invention shown, for example, in FIGS. 4, 5, 6, 7, 8,and 9 and that the spring wire elements 967 of FIG. 9 and 96g of FIG. 10may be replaced by a mesh of spring elements or transverse springelements may be included in the structures 32f and 32g.

From the foregoing description of various embodiments of the presentinvention, it will be apparent to those skilled in the art that thejoint sealing structure fully accomplishes the aims and objectshereinabove set forth. Further, it will be appreciated by those skilledin the art that various modifications and changes may be made in theillustrated forms of the structures without departing from the scope ofthe present invention as defined in the appended claims. For example,the resilient. means in all forms of the invention may be bonded,cemented, heat sealed or the like to the upper ends of the metalextended surface sheet means and such bonding may be in addition tomechanical sealing means such as illustrated in, for example, FIG. 8 andthat the coating illustrated at 19a and 21a in FIG. 1 when applied to,for example, the form of the invention shown in FIG. 4, would also coatthe outer exposed surfaces of the leg portions of the resilient member320.

I claim:

1. A joint forming structure comprising a pair of opposed extendedsurface elements having upper and lower portions adapted to be embeddedin a settable composition, resilient means between at least the upperopposed portion of said elements, and releasable means maintaining saidelements in compressed relation to the resilient means, said releasablemeans comprising means formed from the opposed pair of extended surfaceelements.

2. The invention defined in claim 1 wherein the resilient meanscomprises an elastomeric material.

3. The invention defined in claim 2 wherein the elastomeric materialcomprises a foam rubber like material.

4. The invention defined in claim 2 wherein said elastomeric materialcomprises a resilient elongated channel like structure.

5. The invention defined in claim 4 wherein said channel like member isprovided with a plurality of resilient spring wires embedded therein.

6. A concrete joint forming structure comprising a pair of opposedextended surface metallic elements having an upper portion and a lowerportion, said elements adapted to be embedded in a settable concrete, ahollow channel formed in the upper portion of the said metallic surfaceelements, a resilient element maintained in compression in said channelby said opposed extended surface elements, and means for releasing thecompression on said compressed resilient elernent, said compressionreleasing means comprising a strippable top portion for said hollowchannel.

7. The invention defined in claim 6 wherein the said strippable topportion of the hollow channel is formed with generally parallel scorelines to assist in the removal thereof.

8. The invention defined in claim 6 wherein the outer surfaces of thejoint forming structure are provided with a coating bondable with saidsettable composition.

9. The invention defined in claim 8 wherein said coating comprisesgranular material and an adhesive securing the granular material to saidexposed surfaces of the joint forming structure.

10. The invention defined in claim 9 wherein said granular materialconsists of sand.

References Cited by the Examiner UNITED STATES PATENTS 1,885,391 11/1932Thompson 94-18.2 2,149,291 3/1939 Hofwolt 94-18 2,240,787 5/1941 Kinzer9418.2 3,040,393 6/1962 Dailey 9418.2 X 3,068,763 12/1962 Harza 9418.23,097,579 7/1963 Fujihara 9418 3,124,047 3/1964 Graham 94-18 3,180,2384/1965 Crone 94-18 CHARLES E. OCONNELL, Primary Examiner.

N. C. BYERS, Assistant Examiner.

1. A JOINT FORMING STRUCTURE COMPRISING A PAIR OF OPPOSED EXTENDEDSURFACE ELEMENTS HAVING UPPER AND LOWER PORTIONS ADAPTED TO BE EMBEDDEDIN A SETTABLE COMPOSITION, RESILIENT MEANS BETWEEN AT LEAST THE UPPEROPPOSED PORTION OF SAID ELEMENTS, AND RELEASABLE MEANS MAINTAINING SAIDELEMENTS IN COMPRESSED RELATION TO THE RESILIENT MEANS, SAID RELEASABLEMEANS COMPRISING MEANS FORMED FROM THE OPPOSED PAIR OF EXTENDED SURFACEELEMENTS.